With the development of technology and the progress of society, people are becoming more and more dependent on information exchange and transfer. Display devices, as an important carrier and material base for information exchange and transfer, have become the most sought-after target in the technical field of information photo-electronics.
Quantum dots are extremely small inorganic nanocrystals that are invisible to the naked eye. Quantum dots can emit color light in response to light or electricity. The color of light emitted by a quantum dot is determined by the composition, size and shape of the quantum dot. Usually, smaller quantum dots absorb longer waves, and larger quantum dots absorb shorter waves. For example, a particular sized quantum dot can absorb the blue light which has a short wavelength and emit a color light which has a long wavelength. This causes quantum dots to be able to convert the color of the light emitted by a light source.
Quantum dot display technology has been comprehensively improved in the improvement of color gamut, color control accuracy, and purity of red, green and blue light, and has been considered as a “commanding height” of global display technology and a universally influential revolution in display technology. Quantum dot display technology achieves full gamut display and results in display with accurate colors.
Quantum rods are semi-conductor nanocrystals with a cross-sectional radius smaller than 20 nm and a length of about tens of nanometers. Quantum rods are mostly made up of materials comprising group II-VI elements or group III-V elements. Quantum confinement effect can be observed in quantum-rod materials. Specifically, the movement of electrons and electron holes within a quantum rod can be restricted, which enables the original continuous energy band to become discrete energy levels. Confinement degree of electrons and electron holes varies with the size of the quantum rod, and different confinement degree will result in different discrete energy levels. In response to external excitation, different sized quantum rods can emit light with different wavelengths—different color light.
Quantum rods have the following advantages. The size of quantum rods is adjustable. By tuning the size of quantum rods, the wavelength range of the light emitted can be caused to cover the waveband of the infrared light and the waveband of the entire visible light. The light emitted has a narrow waveband and high saturation degree of color. Quantum-rod materials are efficient in optical wave conversion, stable in property, and easy to be prepared in diverse ways. For example, they can be prepared from various solutions and thus the resources are abundant.
However, when light passes through the irregularly arranged quantum rods, the polarization direction of the emergent light is random. If, when the divergent light from the irregularly arranged quantum rods passes through liquid crystals, the light at each pixel cannot be well controlled any more, light leak will thus occur in the liquid crystal display (LCD) device. A LCD device takes advantage of the optical activity and double refraction of liquid crystals. By controlling the rotation of the liquid crystals with voltage, linearly polarized light passing through an upper polarizer rotates, and then shines out from a lower polarizer (whose polarizer axis is perpendicular to that of the upper polarizer). In this manner, the polarizer and the liquid crystal cell together function as an optical switching. This optical switching, apparently, cannot completely control the light emitted from the irregularly arranged quantum rods.